wifi: always retry ioctl for ifindex

wifi: always retry ioctl for ifindex

ifindex() caches the result of ioctl(SIOCGIFINDEX) and never
retries it, since the interface name strcmp succeeds after the
first call. if the interface does not exist when slstatus starts
(e.g. iwd with default config destroys/recreates interfaces
depending on service state), the ioctl fails and the stale
result is returned on all subsequent calls.

based on a patch by ryhpez, with input from Taha Medhous